Changes relating to the MPI version of escript
The standard OpenMP version of escript is unchanged
- updated data types (Finley_Mesh, Finley_NodeFile, etc) to store meshes
over multiple MPI processes.
- added CommBuffer code in Paso for communication of Data associated
with distributed meshes
- updates in Finley and Escript to support distributed data and operations
on distributed data (such as interpolation).
- construction of RHS in MPI, so that simple explicit schemes (such as
/docs/examples/wave.py without IO and the Locator) can run in MPI.
- updated mesh generation for first order line, rectangle and brick
meshes and second order line meshes in MPI.
- small changes to trunk/SConstruct and trunk/scons/ess_options.py to
build the MPI version, these changes are turned off by default.

A few changes in the build mechanism and the file structure so scons can build release tar files:
* paso/src/Solver has been moved to paso/src
* all test_.py are now run_.py files and are assumed to be passing python tests. they can run by
scons py_tests and are part of the release test set
* escript/py_src/test_ are moved to escript/test/python and are installed in to the build directory
(rather then the PYTHONPATH).
* all py files in test/python which don't start with run_ or test_ are now 'local_py_tests'. they are installed i
by not run automatically.
* CppUnitTest is now treated as a escript module (against previous decisions).
* scons realse builds nor tar/zip files with relvant source code (src and tests in seperate files)
the python tests don't pass yet due to path problems.

+ Fixed incorrect target path in SConstruct file
+ cognac now links with g++ compiled boost rather than intelc compiled boost due to compilation errors with intel c. (Finley will still compile and work with intel c though) - this is the same configuration as the access altix

+ Modified the env (environment) creation for the ia64 platform to include PATH so it no longer complains about not being able to locate the intel compiler. This is related to the previous fix for windows. Seems it is a scons intelc.py bug.

+ Minor modification to how the ENV external environment is initialised. Originally this was done as part of the env = Environment( ENV = ...) construction. Unfortunately this doesn't work properly on windows as it clobbers the path edits performed by the tools = 'intelc'. The end result is icl is not found. Now the env is initialised without the ENV = and they are added in after construction.
I suspect this is a bug in scons itself on the windows platform.

+ NEW BUILD SYSTEM
This commit contains the new build system with cross-platform support.
Most things work are before though you can have more control.
ENVIRONMENT settings have changed:
+ You no longer require LD_LIBRARY_PATH or PYTHONPATH to point to the
esysroot for building and testing performed via scons
+ ACcESS altix users: It is recommended you change your modules to load
the latest intel compiler and other libraries required by boost to match
the setup in svn (you can override). The correct modules are as follows
module load intel_cc.9.0.026
export
MODULEPATH=${MODULEPATH}:/data/raid2/toolspp4/modulefiles/gcc-3.3.6
module load boost/1.33.0/python-2.4.1
module load python/2.4.1
module load numarray/1.3.3

The sparse solver can be called by paso now.
the building has been change to reduce some code redundancy:
now all scons SCscripts are importing scons/esys_options.py which
imports platform specific settings.